IGBT and other power semiconductor devices in the application of photovoltaic inverters

Photovoltaic inverter is the core equipment in the solar power generation system, its main function is to convert the direct current generated by the photovoltaic module into alternating current in line with the requirements of the power grid. In this energy conversion process, power semiconductor devices play a crucial role. This paper will focus on the application of power semiconductor devices such as IGBT in PV inverters.

IGBT in the application of photovoltaic inverters

IGBT (insulated gate bipolar transistor) is one of the most commonly used power semiconductor devices in photovoltaic inverters. Its main applications in PV inverters include.

1.DC/AC inverter circuit: IGBT as the main switching device, through the control of its opening and closing to achieve the conversion of DC to AC.

2.DC/DC boost circuit: In some inverter designs, IGBTs are also used in DC/DC boost circuits to increase the input voltage to match the inverter requirements.

3.Maximum Power Point Tracking (MPPT): IGBTs play a key role in MPPT circuits by adjusting the operating point to achieve the maximum output power of the PV module.

The wide application of IGBT in PV inverters is mainly due to its following characteristics.

1.High input impedance and low on-state voltage drop

2.High voltage and high current

3.Fast switching speed and low losses

4.Positive temperature coefficient, easy to use in parallel

SiC MOSFET Application Trends

In recent years, silicon carbide (SiC) MOSFETs have been increasingly used in photovoltaic inverters. Compared with traditional silicon-based IGBTs, SiC MOSFETs offer the following advantages.

1.lower switching losses: SiC MOSFETs can reduce system losses by 70%. 2. higher operating frequency: SiC MOSFETs have the following advantages.

2.higher operating frequency: can work at 45kHz or higher frequency, while the IGBT usually works at about 16kHz. 3. higher power density: SiC MOSFETs have the following advantages

3.Higher power density: SiC MOSFET inverters can be 80% lighter and smaller. 4.

4.Higher system efficiency: Compared with IGBT solutions, the use of SiC MOSFETs can improve overall system efficiency by about 3%.

Other power semiconductor device applications

In addition to IGBT and SiC MOSFET, other power semiconductor devices in the photovoltaic inverter also has important applications.

1.diode: used for rectification and continuity, SiC Schottky diodes are favoured for their low forward voltage drop and zero reverse recovery characteristics. 2.

2.MOSFETs: In low-voltage applications, such as microinverters, common MOSFETs are still widely used.

3.thyristor: in some high-power photovoltaic inverters, thyristors are still used, mainly for over-voltage protection and other occasions.

Conclusion

Power semiconductor devices are the core components of photovoltaic inverters, directly affecting the performance and efficiency of the inverter. With the continuous progress of photovoltaic power generation technology, the requirements of inverters are getting higher and higher, and IGBT is still the preferred device for mainstream PV inverters due to its excellent overall performance. However, new power devices such as SiC MOSFETs are developing rapidly and are expected to bring more efficient and compact PV inverter solutions in the future. Choosing the right power semiconductor device is critical to improving the overall performance and reliability of the PV system.

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